"This is dangerous to disassemble so we shouldn't have to provide instructions, tools, and documentation on to how to safely disassemble it."
Or
"Normal people can't repair these things, so we shouldn't be required to help normal people repair these things."
Those are exactly the arguments why Apple should provide documentation, parts, and tools! So people don't get hurt!
That being said, guitar amps, specially tube amps are indeed extremely dangerous, not only the caps, but also the 300, 400 and sometimes 500 volts DC around the tubes. You need to be extremely cautious when handling these, specially if they are powered and opened (to check voltages in various points of the circuit for example).
That being said, I've not seen a lot of guitarists actually opening and servicing their amp themselves, even if the circuits tend to be quite simple and easy to maintain/repair (few components, no SMD).